1. Field of the Invention
The present invention relates to a synchronous position correction apparatus for an elevator, and in particular to an improved synchronous position correction apparatus for an elevator which is capable of safely escaping passengers from a car when a synchronous position error occurs in the elevator by moving the car to a neighboring floor and correcting the synchronous position error by using a floor height value of a neighboring floor, for thus normally operating the elevator system.
2. Description of the Conventional Art
FIG. 1 is a diagram illustrating a conventional position control apparatus for an elevator.
As shown therein, the conventional position control apparatus for an elevator includes shielding plates 4A through 4N spacedly disposed in one inner wall of a lifting/lowering path 1, a position detector 3 having a permanent magnet 3A and a lead switch 3B and being disposed in an upper portion of a car 2 for outputting a position detection signal by an interaction with the shielding plates 4A through 4N, an encoder 10 for generating pulses matching with the number of rotations of a motor 9, a main controller 6 for controlling the entire operation of the elevator by outputting a speed command V* for moving the car 2 to a predetermined floor based on the output signals from the position detector 3 and the encoder 10 when a call from the floor or the car 2 is registered, a motor controller 7 for controlling the speed and current of the motor 9 in accordance with the speed command V*, and an inverter 8 for supplying a driving phase voltage to the motor 9 in accordance with the control of the motor controller 7.
The operation for measuring the floor height value of the elevator by using the main controller 6 when initially installing the elevator will now be explained.
When the car 2 is downwardly moved, the car 2 is stopped by a down limit switch DLS, and the car 2 is upwardly moved.
During the running of the elevator, when magnetic field generated by the permanent magnet 3A is shielded by the shielding plates 4A through 4N, the lead switch 3B is turned off. Therefore, the voltage of 48V, which is being supplied to the main controller 6, is blocked. The number of accumulated pulses from the encoder 10 and the number of pulses corresponding to half (125 mm) the length (250 mm) of the shielding plates are added, and the resultant value is stored as the floor height value of a corresponding floor.
When an up limit switch ULS is operated, it is recognized that the storing of the floor height value is finished.
As described above, at the initial stage, the output pulses from the encoder are accumulatively stored in accordance with the running direction (for example, the up movement direction) and recognizes the synchronous position of the car. When a car call occurs, the car is moved in response to the car call, and the synchronous position causes to generate a speed pattern in response to the call, and the speed pattern is used for controlling the position of the car.
In addition, an accurate arriving at a desired floor and an accurate synchronous position must be obtained for preventing the motor from being over-loaded and any accidents to the passengers. However, during the services of the car, there may occur errors due to an external cause. If the error value of the synchronous position exceeds a predetermined level, the normal operation of the car can not be obtained, and the emergency operation is performed.
The absolute position of the car is detected by a hardware sensor, and the car is moved to a neighboring floor, and the door of the elevator is opened, for thus safely escaping the passengers from the car. Thereafter, the synchronous position is corrected, and the elevator is normally operated.
Namely, referring to FIG. 1, if the error value of the synchronous position exceeds a predetermined value, the car is downwardly moved at low speed. When the down limit switch DLS is operated, the car 2 is stopped. When the car 2 is stopped, the synchronous position is corrected as the value related to the position of the down limit switch DLS. Thereafter, the car is normally operated again.
However, in a state that the current position of the car is far from the down limit switch DLS, if a synchronous position error occurs, since the car is moved down to the down limit switch DLS at low speed, during the operation of the car, the passengers must stay in the erroneous car, for thus increasing the electric power consumption.
In order to overcome the above-described problems, a current floor detector is provided for judging the current position of the car.
FIG. 2 is a diagram illustrating a conventional current floor detector for an elevator.
As shown therein, a decelerator 21 is driven by a rope 28 connected with a car 2. A chain 22 is upwardly and downwardly moved by the decelerator 51. A support member 23 connected to the chain 22 and a segment 24 fixed to the support member 23 is upwardly/downwardly moved. A floor detection segment 25 is installed based on the gear formation ratio of the decelerator 21 and is matched with the floor height of a building. Here, two segments 24 and 25 are made of a conductive material. The operation of the current floor detector 20 will now be explained.
When the car 2 is operated, the chain 22 connected with the decelerator 21 is upwardly/downwardly moved, and thus the support member 23 and the segment 24 are upwardly/downwardly moved. When the segment 24 contacts with the floor detection segment 25, the voltage of 48V is supplied to the main controller 6, or the voltage is not supplied thereto. The main controller 6 judges where the car is positioned based on the voltage supply state.
If a synchronous position error occurs, and the floor detection segment 25 of a corresponding floor is operated, the main controller 6 updates the position of the actual floor in which the car 2 is positioned, namely, the current floor is updated, and the synchronous position is corrected as a floor height value of the updated current floor.
After the correction is made, the car is normally operated again.
As described above, if there is provided the current floor detector 20, it is possible to correct the synchronous position in a neighboring floor near which the error occurred. For the corrections above, the decelerator, the rope connected with the car, and the hardware apparatus such as a current floor detector are necessary. In addition, it is necessary to set the fixing position of the floor detection segment and the distance between the floor detection segments which are proportional with respect to the actual height of each floor. In addition, it is further necessary to accurately set the entire length of the current floor detector and the gear formation ratio of the decelerator based on the distance between the uppermost floor and the lowermost floor.
Therefore, in order to install the above-described elements, the fabrication cost is increased. In addition, after the installation of the elevator is made, the above-described values must be accurately set. As the number of floors of a building is increased, it is difficult to install related elements.